Electric field measuring device

ABSTRACT

An electric field measuring device that is particularly suited for being mounted on the nose boom of an aircraft for periodically measuring the atmospheric electric field intensity and orientation. The device includes a rotating assembly that includes a pair of capacitor plates, analog signal processing equipment, digital processing equipment, a slip ring assembly, orientation light transmitter and receiver assemblies and an information light transmitter. All of these elements are mounted on a rotatable shaft that is driven by an electric motor. The light from the rotating information light transmitter is received by a stationary information light receiver, the output of which is applied to the input of a stationary digital receiver and storage device. Floating D. C. power is transmitted by a brush assembly through the slip ring assembly to the rotating electrical equipment.

I United States Patent Wagner et al. Nov. 4, 1975 [54] ELECTRIC FIELDMEASURING DEVICE [57] ABSTRACT [75] Inventors: Peter B. Wagner; James W.Telford;

Richard W. Hanawa 11 f R a 0 cm An electric field measuring device thatIs particularly suited for being mounted on the nose boom of an air-Asslgnee? The Unlted States of Amellca as craft for periodicallymeasuring the atmospheric elecl'eplesemed P) the Secretary of tric fieldintensity and orientation. The device includes Navy, washmgton DC arotating assembly that includes a pair of capacitor [22] Filed: July 51974 plates, analog signal processing equipment, digital processingequipment, a slip ring assembly, orientation pp 486,035 lighttransmitter and receiver assemblies and an information lighttransmitter. All of these elements are [52] US. Cl. 324/72; 324/139;324/144 mounted on a rotafable Shaft that s drivenby an elec- 51 Int.cI. G01R 31/02 motor- The 11gb from mtamg mformam 58 Field of Search 32472, 139, 144; 250/236 light F 1S recelved by a staFlonfiry P tion lightreceiver, the output of which Is applied to [56] References Cited theinput of a stationary digital receiver and storage device. Floating D.C. power is transmitted by a brush UNITED T E PATENTS assembly throughthe slip ring assembly to the rotating Trlngall electrical equipmentPrimary ExaminerAlfred E. Smith Assistant ExaminerMichael J. TokarAttorney, Agent, or FirmR. S. Sciascia; Charles D. B.

Curry 3 Claims, 3 Drawing Figures AM 7 47 49 '0' I07 87 97 I 6 s1DIGITAL INFO. 7

ANALOG ANALOG RECEIVING a 27 59 I 63 CURRENT ANALOG To STORAGE 55 1 I asT0 PBOCE 55m? DIGITAL VOLTAGE PRocEssme 1 7w CIRCUIT cow DIGITAL INFO.s2 '9 ERTER RECEIVING a 57 s5 STORAGE 93 wJwT GROUNDED FLOATING A'RCRAFTAIRCRAFT AIRCRAFT RECORDER POWER POWER SUPPLY SUPPLY wk s? US. PatentNov. 4, 1975 Sheet 1 of 2 3,917,996

ELECTRIC FIELD MEASURING DEVICE BACKGROUND OF THE INVENTION 1. Field ofthe Invention The present invention relates to an electric fieldmeasuring device and more particularly to a very sensitive electricfield measuring device for measuring atmospheric electric fields.

2. Description of the Prior Art Prior rotating electric field measuringdevices have been too bulky and heavy, particularly for mounting onsmall aircraft booms. In addition, they exhibit measuring sensitivitieslimited excessively by noise in brush contacts to rotating shieldsand/or the noise effects of brushes or other electrical coupling uponanalog signal transmission between rotating and stationary members. Thepresent invention overcomes these difficulties by employing uniquelycooperating rotating and stationary assemblies that are compact, lightweight and efficient. Moreover, the present invention employs a uniqueoptical information technique that eliminates brush noise in thetransmitted information signal.

SUMMARY OF THE INVENTION Briefly, the present invention comprises anelectric field measuring device that is particularly suited for beingmounted on the nose boom of an aircraft for periodically measuring theatmospheric electric field intensity and orientation. The deviceincludes a rotating assembly that includes a pair of capacitor plates,analog signal processing equipment, digital processing equipment, a slipring assembly, orientation light transmitter and receiver assemblies andan information light transmitter. All of these elements are mounted on arotatable shaft that is driven by an electric motor. The light from therotating information light transmitter is received by a stationaryinformation light receiver, the output of which is applied to the inputof a stationary digital receiver and storage device. Floating DC. poweris transmitted by a brush assembly through the slip ring assembly to therotating electrical equipment.

STATEMENT OF THE OBJECTS THE INVENTION An object of the presentinvention is to provide an electric field measuring device that iscompact and light weight;

Another object of the present invention is to provide an electric fieldmeasuring device that is accurate and very sensitive;

Still another object of the present invention is to pro vide an electricfield measuring device that minimizes noise in the information signal;

Still another object of the present invention is to provide an electricfield measuring device that may be mounted on an aircraft to measureatmospheric field intensity;

A still further object of the present invention is to provide anelectric field measuring device that may be mounted on the nose of anaircraft to measure the atmospheric field orientation; and

A still further object of the present invention is to provideorientation of the rotating member with respect to the stationary memberby interrupting light from optical devices;

A still further object of the present invention is to provide anelectric field measuring device that optically 2 transmits theinformation signal from a rotating member to a stationary member.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawingswherein:

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENT The purpose of the electric field measuring device of thepresent invention is to measure the electric field in atmosphere. Thisis achieved by positioning the electric field measuring device atdifferent locations within the atmospheric electric field. In accordancewith the present invention this is preferably achieved by mounting theelectric field measuring device on the nose of an aircraft andperiodically measuring the electric field intensity and orientation asthe aircraft flies through the atmosphere. The electric field ismeasured in two of its three vector components, namely the horizontaland vertical components. To achieve this objective the electric fieldmeasuring device is mounted to be cylindrically symmetric with the noseboom of the aircraft wherein the nose boom preferably extends severalfeet in front of the aircraft center. In this manner the charge on theaircraft will have a minimum effect on the field measurement made by theelectric field measuring de vice. It is to be understood that the thirdor axial component of the electric field niay be measured, along witheither the horizontal or vertical components, by orienting a secondelectric field measuring device in a direction that is normal to axis ofthe first electric field measuring device. It is also to be understoodthat the noise rejection system of 'the electric field measuring deviceof the present invention may be used on any device where it is necessaryto transmit power from a stationary member to a rotatingmember and totransmit information from a rotatingv member to a stationary member.

In FIG. 1 is a side elevation of the electric field measuring device 11of the present invention which illustrates the overall system and thearrangement of components. FIG. 2 is a block diagram illustrating theelectrical system of the electric field measuring device 11 of thepresent invention. Referring to FIG. 1, electric field measuring device11 includes a nose cone 13, an outer cylindrical glass insulating sleeve15, a pair of capacitive plates 17 and 19 (see also FIG. 2), an interiorcylindrical shield 21, a centrally positioned outer stationarycylindrical sleeve 23 and a rearwardly positioned outer stationarycylindrical sleeve 25. Capacitive plates 17 and 19 are preferably metalfoil that are mechanically and electrically separated and are attachedto the interior surface of glass insulating sleeve 15.

An elongated hollow shaft 2.7 is rotatably supported by bearings 29, 31and 33 which. are respectively suprotatable hollow shaft 27 by supportmembers 41 and.

Referring to FIGS. 1 and 2 concentrically mounted on the forward sectionof shaft 27 are analog current to voltage converter 45, analogprocessing circuit 47 and analog to digital processing circuit 49,Circuits 45, 47 and 49 are packaged in a cylindrical configuration withan opening in the center. These circuits are packaged to slide overshaft 27 and within cylindrical shield 21 to provide a force fit and arigid interconnection. Electrical plugs, not shown, are provided toelectrically and mechanically interconnect these circuits. Referring toFIG. 1, a collar 51 extends from shaft 27 to support one end of sleevethe other end of whichis supportedby support member 43. An air gap 53 isprovided between sleeve 15 and shield 21 to prevent shorting ofcapacitive plates '15 and 17.

Cylindrically mounted on the rearwardpart of shaft 27, having asmalldiameter, isslip ring assembly 55 which is used to transmit DC.power to circuits 45,47 and 49. This is achieved by transmitting powerto a plurality of slip rings of slip ring assembly 55 from the brushesof brush assembly 57 which are connected to a floatingaircraft powersupply 58. Although not shown,

for reasons of clarity, each slip ring is connected to' a wire whichpasses through the hollow section, of shaft 27 to the .variouselectrical packages 45, 47 and 49 as generally indicated by electricalcable 59. DC. power is transmitted through cable 61 to brush assembly57Shaft 27 is rotated by means of electric motor 63 through gears 65, 67,69 and 71. Gears 67 and 69, which are connected by shaft 73, are made ofa dielectric material, preferably nylon, to prevent electrical couplingbetween the motor armature and the rotating assembly. Electricalcoupling to the rotating assembly is undesirable because the motorarmature, normally hasbrush noise.

The forward end of the electric motor 63 is sup ported by support member75 which is attached to support 39. Connected to the rear end of motor63 is electrical connector assembly 77. A connector plug 79 (having aplurality of pins, not shown) is connected to the assembly 77 and issupported by support member 81 which is connected to sleeve 25. Anelectrical cable 83 is connected from the connector plug 79 to theequipment on board the aircraft.

The pulse modulated light from rotating light transmitter 62 istransmitted to stationary light receiver 85. As illustrated in FIG. 2,the output of stationary light receiver 85 is applied to the input ofstationary digital information receiver and storage circuit 87, theoutput of which is connected to an aircraft recorder 89. The packagecontaining digital information receiver and storage circuit 87 has acylindrical configuration, has a concentric opening 90, and is rigidlyconnected to stationary cylindrical sleeve 23. The concentric opening 90is sufficiently large tov allow free rotation of shaft 27.

Referring to FIGS. 1, 2 and 3, the forward end of the package containingcircuit 87 has extending therefrom stationary pins 95, and 99. Pins 93,and 99 are short and pin 97 is long; Mounted on rotating shaft isorientation light transmitting assembly l0l,having light transmitters103 and 105, and orientation light receiver 107 having light receivers109 and 111. The light transmitter assembly 101 and the light receiverassembly 107 are mounted on support member 1 13 in spaced apartrelationship and with light transmitter 103 in alignment with lightreceiver 109 and light transmitter in alignmentwith light receiver 11 1. The length of short pins 93, 95 and 99 are selected tointerrupt thelight transmitted from light transmitter 105 and the length of pin 97 isselected to interrupt the light from light transmitters 103 as well as105. From this it can be seen that 90, 180, 270 and 360 referencepositions of shaft 27 and the rotating assembly, are electricallydetermined. Also a positive 360 reference is available because pin 97interrupts the light from light transmitter 103 once each revolution orat 360. This provides the required .orientationof the rotating assemblywith respect to the stationary assembly. y I p I The electric fieldmeasuring device 11 of the present invention is prevented fromcollecting condensate, due: to cooling, by passing dry air through boththe swarm: ary' and rotating assembliesf This is indicated bythe dottedline arrows in FIG. 1. Dry'air, which is supplied by an aircraft source,enters through opening in support member 81 and exits throughafplurality of opening 117 formed around the peripheryiof the rearsection of the nose come 13. It shouldbe noted however, that the"section containing th'e slip 'riri'gassembly 55 and brush assembly 57'is sealed and passed through conduit 119. t

The dielectric cylinder 15 is preferably made of glass. Althoughglasshas lesser'dielectric characteristics then teflon, teflon isnotemployed because it can maintain an unwanted charge on the surfacedue to handling and the like. Also capacitor plates 17 and 19 arepreferably mounted on theinterior of'the sleeve to maintain them in adry condition ratherthan on the exterior.

What is claimed is: t

1. An electric field measuring device comprising:

a. a rotatable assembly;

b. a stationary assembly;

0. said rotatable assembly including means'for providing an electricalsignal that contains information defining a condition; y i d. saidelectrical signal being operably connected to an optical transmitter; iN

e. said optical transmitter being operably connected I to said rotatableassembly;

. f. an optical receiver being operably connected to said stationaryassembly and positioned to provide an optical coupling with the opticalsignal from said optical transmitteri g. said rotatable assemblyincluding a sleeve made of dielectric material; h. said means includesfirst and second capacitor 7 plates and signal processing means; i. saidfirst anlrijsecond capacitor plates being spaced apart and operablyconnectedto said sleeve; j. said first and second capacitor plates beingoperably connected to the input of said signal processing 3,917,996 v 6means; and b. an orientation means operably connected to said k. theoutput of said signal processing means being Stationary assembly forinterrupting the transmisoperably connected to the input of said opticalof energy from s,aid ?fiem,ation oPtical mltter assembly to saidorientation optical receiver transmitter. 5 bl ZThd. f assem y e 0clal.m 1 3. The device of claim 2 wherein: a. an orientation opticaltransmitter assembly and an a. said orientation means including aplurality of onemanon oplcal Fecewer assemby bemg f spaced apart pinswherein one of said pins has a y connected to 531d rotatable m y andbemg greater length than the other pins to provide a rota- Spaced apartand spaced flom the rotational axis 0f tional orientation with respectto the other pins.

said rotatable assembly; and

1. An electric field measuring device comprising: a. a rotatableassembly; b. a stationary assembly; c. said rotatable assembly includingmeans for providing an electrical signal that contains informationdefining a condition; d. said electrical signal being operably connectedto an optical transmitter; e. said optical transmitter being operablyconnected to said rotatable assembly; f. an optical receiver beingoperably connected to said stationary assembly and positioned to providean optical coupling with the optical signal from said opticaltransmitter; g. said rotatable assembly including a sleeve made ofdielectric material; h. said means includes first and second capacitorplates and signal processing means; i. said first and second capacitorplates being spaced apart and operably connected to said sleeve; j. saidfirst and second capacitor plates being operably connected to the inputof said signal processing means; and k. the output of said signalprocessing means being operably connected to the input of said opticaltransmitter.
 2. The device of claim 1 including: a. an orientationoptical transmitter assembly and an orientation optical receiverassembly being operably connected to said rotatable assembly and beingspaced apart and spaced from the rotational axis of said rotatableassembly; and b. an orientation means operably connected to saidstationary assembly for interrupting the transmission of energy fromsaid orientation optical transmitter assembly to said orientationoptical receiver assembly.
 3. The device of claim 2 wherein: a. saidorientation means including a plurality of spaced apart pins wherein oneof said pins has a greater length than the other pins to provide arotational orientation with respect to the other pins.